Basilar artery blood flow velocity changes in patients with panic disorder following 35% carbon dioxide challenge

PurposeWe compared the mean basilar artery blood flow velocity (BABFV) between patients with panic disorder and healthy subjects both at rest and immediately following carbon dioxide (CO2) challenge, and examined the effects of treatment on BABFV.MethodsTwenty four patients with panic disorder with or without agoraphobia and 12 healthy comparison subjects were studied. Visual Analog Anxiety Scale was used to evaluate the anxiogenic effect of 35% CO2 inhalation. Mean BABFV was monitored using transcranial Doppler ultrasonography at rest and 10, 20, 30, 60, 90, 120 s after 35% CO2 challenge both before and after four weeks treatment with paroxetine.ResultsThe hemodynamic response pattern of basilar artery to CO2 inhalation was significantly different between two groups. CO2 rapidly triggered blood flow velocity in basilar artery amongst panic patients but not in healthy comparisons. The mean time to normalization of BABFV was significantly longer in panic patients. Four weeks of treatment with paroxetine led to a significantly reduced mean BABFV after 35% CO2 inhalation in comparison with pretreatment.ConclusionsPatients with panic disorder had impaired cerebral regulatory mechanisms observed as a change in response characteristics in BABFV in response to CO2 inhalation. Treatment with paroxetine reduced the increase of BABFV seen in patients after the CO2 challenge.